Apparatus and method for determining loft time and speed

ABSTRACT

The invention detects loft time and/or speed of a vehicle and/or person during activities of moving and jumping. A loft sensor detects leaving the ground and returning to the ground. A microprocessor subsystem converts the sensed information to determine a loft time. A display shows the recorded loft time to a user of the system. A speed sensor can detect speed for selective display to the user, and height may also be determined during airtime.

This application is a continuation of commonly-owned U.S. Ser. No.08/764,758 (now U.S. Pat. No. 5,960,380), filed Dec. 12, 1996, which isa continuation of U.S. Ser. No. 08/344,485 (now U.S. Pat. No.5,636,146), filed Nov. 21, 1994, each of which are incorporated hereinby reference.

FIELD OF THE INVENTION

The invention relates generally to the measurement of the loft time andspeed of a vehicle relative to the ground. Such measurements areparticularly useful in sporting activities like skiing and mountainbiking where users desire information relating to their speed and/orloft, or “air” time.

BACKGROUND OF THE INVENTION

It is well known that many skiers enjoy high speeds and jumping motionswhile traveling down the slope. High speeds refer to the greater andgreater velocities which skiers attempt in navigating the slopesuccessfully (and sometimes unsuccessfully). The jumping motions, on theother hand, include movements which loft the skier into the air.Generally, the greater the skier's speed, the higher the skier's loftinto the air.

The interest in high speed skiing is apparent simply by observing thevelocity of skiers descending the mountain. The interest in the loftmotion is less apparent; although it is known that certain enthusiasticskiers regularly exclaim “let's catch some air” and other assortedremarks when referring to the amount and altitude of the lofting motion.

The sensations of speed and jumping are also readily achieved in othersporting activities, such as in mountain biking. Many mountain bikers,like the aforementioned skiers, also crave greater speeds and “air”time.

However, persons in such sporting activities typically only have aqualitative sense as to speed and loft or “air” time. For example, atypical snowboarding person might regularly exclaim after a jump thatshe “caught” some “big sky,” “big air” or “phat air” without everquantitatively knowing how much time really elapsed in the air.

It is, accordingly, an object of the invention to provide apparatus andmethods for determining the “air” time of participants in sportingactivities such as skiing and mountain biking.

It is another object of the invention to provide apparatus and methodsfor determining the speed of participants in sporting activities such asskiing and mountain biking.

It is yet another object of the invention to provide improvements tosporting devices which are ridden by sporting participants, and whichprovide a determination of speed and/or loft time of the device.

These and other objects of the invention will become apparent in thedescription which follows.

SUMMARY OF THE INVENTION

The invention concerns the detection and display of loft, or “air” timeand/or speed of vehicles such as sporting vehicles, includingnon-motorized vehicles like skis, bikes, and snowboards. The inventionthus provides a visual and quantitative measure of how much “air” timeand, in certain aspects, how fast a user moves in a particular activity.

The invention provides, in one aspect, apparatus for determining theloft time of a moving vehicle off of a surface. A loft sensor senses afirst condition that is indicative of the vehicle leaving the surface,and further senses a second condition indicative of the vehiclereturning to the surface. A microprocessor subsystem, e.g., amicrocontroller, determines a loft time that is based upon the first andsecond conditions, and the loft time is thereafter displayed to a userof the apparatus by a display, e.g., a LCD or LED display. Preferably, apower module such as a battery is included in the apparatus to power theseveral components. In addition, a housing preferably connects andprotects the microprocessor subsystem and the user interface; andfurther such that the housing is attachable to the vehicle.

According to another aspect, the invention includes memory for storinginformation representative of at least one of the following: (i) thefirst and second conditions, (ii) the loft time, (iii) a speed of thevehicle, (iv) successive records of loft time, (v) an average loft time,(vi) a total loft time, (vii) a dead time, (viii) a real activity time,and (ix) a numerical ranking of successive records.

One preferred aspect of the invention includes a speed sensor, connectedto the microprocessor subsystem, which senses a third condition that isindicative of a velocity of the vehicle. In this aspect, themicroprocessor subsystem includes means for converting the thirdcondition to information representative of a speed of the vehicle.Accordingly, the apparatus provides a user with both loft time, e.g.,“air” time, and a speed of the vehicle.

In yet another aspect, the display of the invention can displayselective information, including one or more of the following: the lofttime; a speed of the vehicle; a peak loft time; an average loft time; atotal loft time; a dead time; a real activity time; an average speed; anindication that loft time is being displayed; an indication that speedis being displayed; an indication that dead time is being displayed; anindication that real activity time is being displayed; successiverecords of loft information; successive records of speed information; adistance traveled by the vehicle; a height achieved by the vehicle offof the surface; and an indication of a number of a successive recordrelative to all successive records.

In still another aspect, the invention includes a user interface forproviding external inputs to the apparatus, including one or more of thefollowing: a start/stop button for selectively starting and stopping theacquisition of data by the apparatus; a display-operate button foractivating the display means selectively; a speed/loft toggle button foralternatively commanding a display of loft time information and speedinformation of the vehicle; means for commanding a display of successiverecords of loft time information selectively; means for commanding adisplay of successive records of speed information selectively; meansfor commanding a display of information corresponding to average lofttime; means for commanding a display of information corresponding toaverage speed; means for commanding a display of total loft time; meansfor commanding a display of dead time; means for commanding a display ofdistance traveled by the vehicle; means for commanding a display ofheight achieved by the vehicle off of the surface; and means forcommanding a display of real activity time.

Preferably, the microprocessor subsystem of the invention includes aclock element, e.g., a 24-hour clock, for providing informationconvertible to an elapsed time. Accordingly, the subsystem can performvarious calculations, e.g., dead time, on the data acquired by theapparatus for display to a user.

In another aspect, the loft sensor is constructed with one of thefollowing technologies: (i) an accelerometer that senses a vibrationalspectrum; (ii) a microphone assembly that senses a noise spectrum; (iii)a switch that is responsive to a weight of a user of the vehicle; (iv) avoltage-resistance sensor that generates a voltage indicative of a speedof the vehicle; and (v) a plurality of accelerometers connected forevaluating a speed of the vehicle.

In a preferred aspect, the loft sensor of the invention senses aspectrum of information, e.g., a vibrational or sound spectrum, and themicroprocessor subsystem determines the first and second conditionsrelative to a change in the spectrum of information. Further, themicroprocessor subassembly interprets the change in the spectrum todetermine the loft time.

For example, one aspect of a loft sensor according to the inventionincludes one or more accelerometers that generate a vibrational spectrumof the vehicle. In such an aspect, the first and second conditionscorrespond to a change in the vibrational spectrum. By way of anotherexample, one loft sensor of the invention includes a microphonesubassembly that generates a noise spectrum of the vehicle; and, in thisaspect, the first and second conditions correspond to a change in thedetected noise spectrum. Because these spectrums are influenced by theparticular activity of a user, e.g., standing in a ski line, amicroprocessor subsystem of the invention preferably includes means forassessing boundary conditions of the spectrum and for excluding certainconditions from the determination of loft time. Accordingly, if a skieris in a lift line, such conditions are effectively ignored. One boundarycondition, therefore, according to an aspect of the invention, includesan elapsed time between the first condition and the second conditionthat is less than approximately 500 ms; such that events that are withinthis boundary condition are excluded from the determination of lofttime. One other boundary condition, in another aspect, includes anelapsed time between the first condition and the second condition thatis greater than approximately five seconds; such that events that areoutside this boundary condition are excluded from the determination ofloft time. Because these boundary conditions are important in theaspects of the invention which utilize a spectrum of information, theapparatus preferably utilizes a user interface for providing selectiveexternal inputs to the microprocessor subsystem and for adjusting theboundary conditions selectively.

In still another aspect of the invention, the microprocessor subassemblyincludes means for determining a pitch of the spectrum by determining abest-fit sine wave to a primary frequency of at least part of thespectrum and means for correlating the pitch to a vehicle speed.Accordingly, the invention can detect spectrum information and correlatethat information to a speed of the vehicle. Typically, a higher pitchfrequency corresponds to a higher vehicle speed and a lower pitchfrequency corresponds to a lower vehicle speed. However, in anotheraspect, the selected pitch frequency can be calibrated relative to aselected vehicle and speed.

The invention also provides, in another aspect, means for storinginformation including look-up tables with pitch-to-speed conversions fora plurality of vehicles. This is useful because different vehicles havedifferent associated noise and/or sound spectrums associated with thevehicle. Accordingly, the invention in this aspect includes memory forstoring the respective calibration information of the different vehicles(typically in a look-up table format) so that a user can utilize theinvention on different vehicles and still determine speed accurately.Specifically, a particular pitch is associated with a particular speedfor a particular vehicle; and that association is selectively made bythe user.

The vehicles which are preferably used, according to the invention,include (i) a snowboards, (ii) snow skis, (iii) water skis, (iv) skisfor ski jumping, and (v) skis for ski flying. However, in certainaspects of the invention, a human vehicle can be used; although theprocessing power required to accurately process speed and/or loftinformation in this aspect is significantly increased.

In several aspects of the invention, the microprocessor subassemblyincludes one or more of the following: means for selectively startingand stopping the acquisition of data by the apparatus; means forresponding to an external request to activate the display means; meansfor responding to an external request to alternatively display the lofttime and a speed of the vehicle; means for calculating a speed of thevehicle; means for responding to an external request to displaysuccessive records of loft time information; means for responding to anexternal request to display successive records of speed information;means for determining an average speed; means for determining a totalloft time; means for determining a dead time; means for responding to anexternal request to display information corresponding to an average lofttime; means for responding to an external request to display informationcorresponding to an average speed; means for responding to an externalrequest to display a total loft time; means for responding to anexternal request to display a dead time; means for responding to anexternal request to display a distance traveled by the vehicle; meansfor responding to an external request to display a height achieved bythe vehicle off of the surface; and means for responding to an externalrequest to display a real activity time.

The invention also provides certain improvements to sporting vehicles ofthe type ridden by a user on a surface (e.g., sporting vehicle such as(i) snowboards, (ii) snow skis, (iii) water skis, (iv) skis for skijumping, and (v) skis for ski flying). The improvements include, in oneaspect, a speed sensor having (i) a voltage-measuring circuit includinga pair of conductors arranged to contact the surface so that the surfaceis part of the circuit, and (ii) an electromagnet for selectivelygenerating a magnetic field on the circuit, wherein a voltage generatedby the circuit is proportional to a speed of the vehicle. In such anaspect, the microprocessor subsystem determines a speed of the vehiclethat is based upon the voltage, and that speed is displayed to a user.

The invention also provides certain methodologies. For example, in oneaspect, the invention provides a method for determining the loft time ofa moving vehicle off of a surface, comprising the steps of: (1) sensingthe vehicle leaving the surface at a first time; (2) sensing the vehiclereturning to the surface at a second time; (3) determining a loft timefrom the first and second times, and (4) displaying the loft time to auser of the apparatus.

The invention is next described further in connection with preferredembodiments, and it will be apparent that various additions,subtractions, and modifications can be made by those skilled in the artwithout departing from the scope of the invention

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention may be obtained byreference to the drawings, in which:

FIG. 1 illustrates a system constructed according to the invention fordetermining loft and speed of a sporting vehicle carrying the system;

FIGS. 2, 2A and 2B show illustrative uses for the system 10 shown inFIG. 1;

FIG. 3 illustrates a user interface and display suitable for use in thesystem of FIG. 1;

FIG. 4 is a representative vibrational spectrum, shown illustratively,for calculating “air” or loft time in accord with the invention;

FIG. 5 shows a microphone-based loft sensor constructed according to theinvention and which is suitable for use in the system of FIG. 1;

FIG. 6 shows a switch-based loft sensor constructed according to theinvention and which is suitable for use in the system of FIG. 1;

FIG. 7 shows a capacitance-based loft sensor constructed according tothe invention and which is suitable for use in the system of FIG. 1;

FIG. 8 schematically illustrates electronics, constructed according tothe invention, for converting a varying capacitance, e.g., thecapacitance derived from the loft sensor of FIG. 7, to informationsuitable for calculating “air” time;

FIG. 9 schematically illustrates alternative electronics, constructedaccording to the invention, for converting a varying capacitance, e.g.,the capacitance derived from the loft sensor of FIG. 7, to informationsuitable for calculating “air” time;

FIG. 10 schematically illustrates a microprocessor subsystem constructedaccording to the invention and which is suitable for use in the systemof FIG. 1;

FIG. 11 illustrates one exemplary pitch-detection process, in accordancewith the invention, which is used to determine the speed of a vehicle;

FIG. 12 illustrates a Doppler-based approach to sensing speed inaccordance with the invention;

FIG. 12A shows a laser-based Doppler speed sensor constructed accordingto the invention;

FIG. 12B shows an ultrasonic-based Doppler speed sensor constructedaccording to the invention;

FIG. 13 illustrates an accelerometer-based speed sensor constructedaccording to the invention and which is suitable for use as both thespeed and loft sensors of FIG. 1;

FIG. 14 schematically illustrates process methodology of converting aplurality of acceleration values to speed, in accord with the invention;

FIG. 14A schematically illustrates a process methodology of calculatingspeed, direction, and vehicle height, in accord with the invention, byutilizing the accelerometer-based sensors of the invention;

FIGS. 15 and 15A illustrate a pressure-based speed sensor constructedaccording to the invention;

FIGS. 16 and 16A illustrate a magnetic/voltage-based speed sensorconstructed according to the invention;

FIG. 16B shows relative motions, magnetic field directions, and voltagesassociated with the sensor of FIGS. 16 and 16A;

FIG. 17 illustrates an improvement to a snowboard in accord with theinvention; and

FIG. 18 illustrates one use of the invention for detecting speed, “air,”and distance in the sport of ski flying (or ski jumping) in accord withthe invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

FIG. 1 illustrates a system 10 constructed according to the invention. Amicroprocessor subsystem 12 controls the system 10 and connects to auser interface 14, a display 16, speed sensor 18 and loft sensor 20. Apower supply 22, e.g., a battery, provides power to the system 10 andconnects to the components 12,14,16,18 and 20 via appropriate electricalinterconnections (not shown). The microprocessor subsystem 12 includesmemory 13 for storing data acquired by the system 10.

The system 10 is incorporated into a relatively small housing, shown bythe outline 24. The housing 24 is preferably arranged to protect thecomponents 12,14,16,18 and 20 from the elements of nature—such as rain,snow, sand and dust, each of which is expected during the ordinarycourse of usage on a ski slope and/or mountain bike trail. In addition,the housing 24 is attachable to a vehicle, such as a ski or mountainbike, by means such as a glue or a mechanical mount, e.g., screws.Alternatively, the housing (and hence the system 10) is incorporatedintegrally with the vehicle, such as inside a ski, such that only thedisplay 16 and user interface 14 are visible and accessible.

Briefly, the invention shown in FIG. 1 operates as follows. The housing24 is attached or mounted to a sporting device, such as a ski ormountain bike, such that a user of the ski or mountain bike can accessthe system 10. During motion of the ski or mountain bike, the speedsensor 18 sends velocity information (over communication line 11 a) tothe microprocessor subsystem 12; while the loft sensor 20 sends loft or“air” time information (over communication line 11 b) to themicroprocessor subsystem 12. The speed information and loft timeinformation are processed by the microprocessor subsystem 12 to quantifyactual speed, e.g., in miles per hour, and actual loft time, e.g., inseconds. The actual speed and loft time are thereafter stored ininternal memory 13 until, at least, the speed and time data are accessedby a user of the system 10. Upon access through the user interface 14(communicating with the microprocessor subsystem 12 via communicationline 11 c), a user of the system 10 can command the display of the speedand loft time data (sent across communication line 11 d) on the display16 in order to evaluate his or her performance in the sporting activity.

In an alternative embodiment, the speed and loft information can bestored prior to processing by the microprocessor subsystem 12; and laterpost-processed for display on the display 16 when commanded by a user ofthe system 10. Such an embodiment may be useful to conserve energy andto perform calculations to quantify the speed and loft data in a “batch”mode, such as known to those skilled in the art.

The system 10 of FIG. 1 preferably includes both of the speed sensor 18and loft sensor 20; although it is not necessary for both sensors to bepresent in accord with the invention. Rather, in certain embodiments ofthe invention, only the loft sensor 20 is present within the system 10;and in certain other embodiments of the invention, only the speed sensor18 is present within the system 10. Accordingly, in these embodiments,only the loft data or speed data, respectively, are available to a userof the system because the sensor which measures the information isabsent.

FIGS. 2, 2A and 2B show typical uses of the system 10 illustrated inFIG. 1. In particular, FIG. 2 shows the system 10 mounted onto a ski 26.As is normal, the ski 26 is mounted to a skier 28 (for illustrativepurposes, the skier 28 is only partially illustrated), via a ski boot 30and binding 30 a, and generally descends down a ski slope 32 with avelocity 34. Accordingly, one use of the system 10 is to calculate thepeak speed of the ski 26 (and hence the skier 28) over a selectableperiod of time, e.g., during the time of descent down the slope 32.

Another use of the system 10 of FIG. 1 is to calculate the loft, or“air” time of the ski 26 (and hence the user 28) during the descent downthe slope 32. Consider, for example, FIG. 2A, which illustrates thepositions of the ski 26′ and skier 28′ during a lofting maneuver on theslope 32′. The ski 26′ and skier 28′ speed down the slope 32′ and launchinto the air 36 at position “a,” and later land at position “b” inaccord with the well-known Newtonian laws of physics. The system 10calculates and stores the total “air” time that the ski 26′ (and hencethe skier 28′) experience between the positions “a” and “b” so that theskier 28′ can access and assess the “air” time information.

FIG. 2B illustrates the system 10 mounted onto a mountain bike 38. FIG.2B also shows the mountain bike 38 in various positions during movementalong a mountain bike race course 40 (for illustrative purposes, thebike 38 is shown without a rider). At one location “c” on the racecourse 40, the bike 38 hits a dirt mound 42 and catapults into the air44. The bike 38 thereafter lands at location “d.” As above, the system10 provides information to a rider of the bike 38 about the speedattained during the ride around the race course 40; as well asinformation about the “air” time between location “c” and “d.”

User Interface and Display

With further reference to FIG. 1, the display 16 can be one of anyassortment of displays known to those skilled in the art. For example,liquid crystal displays (LCDs) are preferred because of their low powerdraw (for example, LCDs utilized in digital watches and portablecomputers are appropriate for use with the invention). Other suitabledisplays can include an array of light emitting diodes (LEDs) arrangedto display numbers.

FIG. 3 illustrates a user interface 50 and display 52 constructedaccording to the invention and which are suitable for use, respectively,as the interface 14 and display 16 of FIG. 1. Outline 54 illustrates theoutline of a system constructed according to the invention, e.g., thehousing outline 24 of the system 10 of FIG. 1. In order for a user ofthe system to access information within the system, user interface 50includes control buttons. For example, with reference to FIG. 3, oneembodiment of the user interface 50 includes a start/stop button 58, adisplay-operate button 60, and a speed/loft toggle button 62. Thesebuttons operate as follows:

A user presses the start/stop button 58 at the start of activity—such asat the start of skiing down a slope or biking down a trail—and pressesthe button 58 at the completion of activity to cease the acquisition ofdata (as described in more detail below).

A user pressed the display-operate button 60 to activate the display 52so that a user can view recorded information from the sporting activityon the display 52. Accordingly, the display 52 is normally OFF—and notdrawing power from the associated power source (e.g., the power source22 of FIG. 1)—and is turned ON only when a user activates thedisplay-operate button 52. The ON and OFF display conditions arepreferably obtained in one of two ways: in one embodiment of theinvention, the display 52 automatically turns OFF after a preselectedtime through the control of the microprocessor subsystem 12 of FIG. 1;or, in an alternative embodiment, the display 52 remains activated untila user again presses the display-operate button 60.

A user presses the speed/loft toggle button 62 to sequentially commandthe display, respectively, of information about speed and loft time. Forexample, if the display 52 currently displays speed information, a usercan instead command the display of loft time information by pressing thespeed/loft toggle button 62 once. If, on the other hand, the display 52currently displays loft information, a user can instead command thedisplay of speed information by pressing the speed/loft toggle button 62once. Preferably, one portion 64 of the display denotes whether speed orloft information is being displayed. For example, as illustrated, a “L”letter denotes that loft information is being displayed. An “S” letterlikewise denotes that speed information is being displayed. Forillustrative purposes, the “air” time is also displayed in FIG. 3 as2.46 seconds, which represents the “air” time of a typical ski jump.

It is important to note that one embodiment of the invention does notinclude the speed/loft toggle button 62 because, as noted earlier,certain embodiments of the invention do not include both the speedsensor and loft sensor. In such an embodiment, it is unnecessary toinclude a toggle button 62.

The display 52 of FIG. 3 also shows another feature of the invention,namely that a system constructed according to the invention preferablycalculates and stores successive records relating to speed and loftinformation relative to a user's activity. For example, a skier maycatch “air” time more than once during a given activity; and the systemof the invention can store successive loft times for access by the user.Most often, the peak “air” time is displayed, by default. However,certain users wish to evaluate successive loft time information and,accordingly, the system 10 of FIG. 1 preferably determines and storesthe successive information (described in greater detail below). A usercan access the successive loft time information by toggling acombination of the buttons 58-62, such as known to those skilled in theart (e.g., a combination of holding one button down while pressinganother button); or by including yet another button 66 on the userinterface 50. A display portion 68 of the display 52 shows a numbercorresponding to the sequential information on display. For example, theillustrated “1” number means that the highest “air” time record iscurrently being displayed; while a number greater than one means that aloft time other than the highest loft time is being displayed. Inaddition, the highest number displayed within the portion 68 refers tothe total number of “air” times for the selected activity period (thusfor example a user can determine the total number of jumps achieved fora given day).

In still another embodiment of the invention, successive speedinformation can be displayed much the way successive “air” timeinformation is stored and displayed, described above. To view the speedinformation, the speed/loft toggle button 62 is pressed once to display“S” in the display portion 64, and a user can toggle button 66 to viewthe successive speed records as denoted by the number in display portion68. However, this information is not deemed very useful except under avery few circumstances—since a user generally moves with some velocityduring a given activity—and thus, generally, the peak speed achievedduring a given activity is normally displayed on the display 52 whencommanded by the speed/loft toggle button 62.

In an alternative embodiment, a button 67 is used to alter the modes ofthe system so that other information such as average “air” time may becalculated and displayed by the invention. For example, FIG. 3illustrates a display portion 69 that shows a letter “A,” correspondingto information relating to averages. Thus, for a particular sportingactivity, a user can press button 69 to display “air” time as a runningaverage of all the successive “air” times (in such an embodiment, thedisplay portion 68 is preferably OFF because the information displayedin portion 68 refers to successive peak information). To access the peak“air” time information, the button 67 is pressed once again, causing themicroprocessor subsystem 12 to change the display information fromintegrated average values to peak values (accordingly, the displayportion 69 preferably shows a “P” to identify to the user that peakinformation is being displayed; and the display portion 68 is preferablyON in this “peak” mode to denote which successive record is beingdisplayed). To access integrated information—e.g., the total “air” timefor a given day—the button 67 is pressed once again, causing themicroprocessor subsystem 12 to show the integrated “air” or speedinformation (depending on the toggle of the speed/loft toggle button62). Integrated values are preferably displayed by indicating to theuser a “T” (for total) in the display portion 69.

It should be clear to those skilled in the art that other buttons and/orcombinations of buttons can be incorporated within the user interface 50within the scope of the invention. The microprocessor subsystem 12 ofFIG. 1 stores much information during the sporting activity and whichcan be converted to different forms, e.g., averages, peaks, and totals.In accord with the invention, different buttons and combinations ofbuttons can be used to access all of the available information. Inaddition, other information can be denoted, for example, within thedisplay portion 69 to identify the different types of informationavailable within the system.

For example, yet another form of information which may be of interest tosporting persons is the “dead” time, i.e., the time that the person isnot skiing or biking during the day. For example, a person who hangs outin the bar during part of the afternoon will not have a high efficiencyfactor for actual ski time as compared to the available ski time. Thisefficiency information is available in accord with the invention becausethe microprocessor subsystem 12 of FIG. 1 preferably includes a clockelement (readily known to those skilled in the art) for indicatingprocessed time over a selectable period (the microprocessor subsystem 12can in fact include a 24-hour clock element, much the way a digitalwrist-watch includes 24-hour information). Accordingly, a user can startthe system 10 of FIG. 1 at the beginning of the day by pressing thestart/stop button 58, and stop the collection of data at the end of theday by again pressing the start/stop button 58. The microprocessorsubsystem 12 keeps track of the elapsed time between the start and stopof the system (i.e., the selectable time period), thereby providingmeans for determining the user's “dead” time for the day. That is, themicroprocessor subsystem 12 calculates “ dead” time by intelligentlycalculating the total time lapse within which a vibrational noisespectrum (described in more detail below in connection with FIG. 4) ispresent within the selectable time period; and dividing that total timelapse by the selectable time period to obtain a ratio of the realactivity time versus the user's dead time (for example, a ratio of 80%means that the sporting person skied for 80% of the day). Dead timeinformation is thereafter easily determined by subtracting 80% from100%, to get 20% dead time. The dead time information is shown, forexample, by toggling the button 67 to a dead time mode, denoted as “D,”in the display portion 69, and displaying the dead time as a percentagein the display 52. Alternatively, the real activity time is displayed asa percentage in the display 52 by toggling the button 69 until “R” showsup in the display portion 69.

Loft Sensor

With further reference to FIG. 1, the loft sensor 20 may be constructedby several known components. Preferably, the sensor 20 is either anaccelerometer or a microphone assembly. Alternatively, the sensor 20 maybe constructed as a mechanical switch that detects the presence andabsence of weight onto the switch. Each of these alternatives isdescribed below.

Loft Sensor: Accelerometer Embodiment

An accelerometer, well known to those skilled in the art, detectsacceleration and provides a voltage output that is proportional to thedetected acceleration. Accordingly, the accelerometer sensesvibration—particularly the vibration of a vehicle such as a ski ormountain bike—moving along a surface, e.g., a ski slope or mountain biketrail. This voltage output provides an acceleration spectrum over time;and information. about loft time can be ascertained by performingcalculations on that spectrum. Specifically, the microprocessorsubsystem 12 of FIG. 1 stores the spectrum into memory 13 and processesthe spectrum information to determine “air” time.

FIG. 4 illustrates a graph 70 of a representative vibrational spectrum72 that is stored into the microprocessor subsystem 12 (FIG. 1). Thevertical axis 74 of the graph 70 represents voltage; while thehorizontal axis 76 represents time. At the beginning of activity 77—suchas when a user of a system constructed according to the inventionpresses the start/stop button 58 (see FIG. 3)—the loft sensor 20 of FIG.1 begins acquiring data and transferring that data to the microprocessorsubsystem 12 via communication lines 11 b. This data appears highlyerratic and random, corresponding to the randomness of the surfaceunderneath the vehicle (e.g., ski or vehicle). At time “t1,” the user ofthe system lofts into the air, such as illustrated as location “a” inFIG. 2A and as location “c” in FIG. 2B; and lands some time later attime “t2,” such as illustrated as location “b” in FIG. 2A and aslocation “d” in FIG. 2B. The vibrational spectrum between t1 and t2 iscomparatively smooth as compared to the spectrum outside this regionbecause the user's sporting vehicle (e.g., the ski or mountain bike) isin the air and is not therefore subjected to the random vibrations ofthe road or ski slope. Accordingly, this relatively smooth spectrumbetween t1 and t2 can be readily discerned from the rest of the spectrumby the microprocessor subsystem 12 and evaluated for “air” time:specifically, “air” time is t2−t1.

FIG. 4 also shows that the spectrum stops at the end 78 of the sportingactivity, such as when the user of the system again presses thestart/stop button 58, FIG. 3.

In one embodiment of the invention, a user can simply start the system10 of FIG. 1 at the beginning of the day, by toggling the start/stopbutton 58, and stop the system 10 at the end of the day, by againtoggling the start/stop button 58. The issue here, however, is thatthere may be apparent “air” times between the starting and stopping ofthe system which is not, in fact, the “air” time of interest. Forexample, standing in line at a ski lift represents a period within whichthe spectrum 72 appears smooth, and might be mistaken for “air” time.Accordingly, the microprocessor subsystem 12 of the invention preferablyincludes process boundary conditions within which “air” time will beexcluded. For example, one practical boundary condition is: if thespectrum between any given “t1” and “t2” time (FIG. 4) is greater thanfive seconds, then exclude that time from memory as actual “air” time.Thus, each time the skier stands in line, that smooth spectrum which isbeing processed by the system is ignored.

Another boundary condition, for example, concerns the type of skierusing the system. Some skiers often make quick jump turns down themountain. These would normally show up as mini “air” times. Thus, inaccord with another aspect of the invention, another boundary conditionis: if the spectrum between any given “t1” time and “t2” time (FIG. 4)is less than 500 ms, then exclude that time from memory as actual “air”time. Accordingly, each jump turn will not be included in the total“air” time for the day, as is expected by users of the system.

The invention preferably includes an adjustment mechanism to adjustthese boundary conditions (e.g., the five seconds maximum and the 0.5second minimum) so that such conditions can be adjusted and optimized toindividual users. Accordingly, in one embodiment of the invention,certain of the buttons 58-67 of FIG. 3 can be used in combination to setthe maximum and minimum boundary conditions. Alternatively, one or moreadditional buttons can be included within the user interface of FIG. 3to provide the adjustment mechanism.

Another embodiment of the invention internally resets the start/stopbutton 58 when the system senses the lack of spectral information for apreselected period of time. Thus, after the preselected period, thesystem has an automatic time-out, resulting in the microprocessorsubsystem 12 resetting itself as if the start/stop button 58 werepushed.

Accelerometers are commercially available and are relatively cheapitems. They are also small, so that all of the components 12, 14, 16 and20 may easily fit within a small, lightweight housing. Suitableaccelerometers include those accelerometers shown and described inconnection with FIGS. 13, 14 and 14A.

Loft Sensor: Microphone Embodiment

A microphone, also well known to those skilled in the art, detects soundwaves and provides a voltage output that is responsive to the detectedsound waves. Accordingly, a microphone, like the accelerometer, sensesthe vibration of a vehicle, such as a ski or mountain bike, moving alonga surface, e.g., a ski slope or mountain bike trail. By way of analogy,consider putting one's ear flat onto a desk and running an object acrossthe desk. As one can readily determine, the movement of the object onthe desk is readily heard in the ear. Likewise, a microphone as the loftsensor 20 readily “hears” the vibrational movements of the vehicle onthe surface. Therefore, like the aforementioned accelerometer, avibrational spectrum such as shown in FIG. 4 is generated by themicrophone loft sensor during a user's sporting activity. As above, themicroprocessor subsystem 12 utilizes the spectrum to determine “air”time.

Like accelerometers, microphones are also commercially available and arerelatively cheap. They are also small, so that all of the components 12,14, 16 and 20 may easily fit within a small, lightweight housing.

FIG. 5 illustrates one embodiment of a microphone assembly 80 suitablefor use with the invention. Specifically, a system 82 constructedaccording to the invention mounts, for example, to a ski 84 (forillustrative purposes, only the loft sensor portion 80 andmicroprocessor subsystem 81 are shown as part of the system 82 eventhough other components such as the display and user interface arepresent within the system 82). The microphone assembly 80 preferablyincludes a tube portion 86 to funnel the sound waves 88 coming from theski surface 90 to the microphone element 92, e.g., a piezoelectricelement known to those skilled in the art. During operation, thevibrational motion caused by the ski's interaction with the surfaceunderneath the ski generates the sound waves 88 detected by the element92, which converts the sound waves to voltages. These voltages aresampled and stored in the microprocessor subsystem 12 so that theinformation can be processed to extract the “air” information.

Depending on the sensitivity of the accelerometers and microphoneassemblies, described above, it is feasible to attach the system of theinvention directly to a user of the system as opposed to the vehicle.The vibrational or sound information is transmitted through the user tosome degree while the user is on the ground, and such information can beused, as above, to calculate “air” time. Accordingly, one embodiment ofthe invention indudes a system which measures “air” time that mountsdirectly to a user rather than to the vehicle, e.g., a ski.

Loft Sensor: Weight Switch Embodiment

In still another embodiment of the invention, the sensor 80 of FIG. 1can be a switch that rests below the boot of the ski, e.g., the boot 30of FIG. 2, and that senses pressure caused by the weight of the userwithin the boot. That is, when the skier is on the ground, the bootsqueezes the switch, thereby closing the switch. The closed switch isdetected by the microprocessor subsystem 12 (FIG. 1) as a discreteinput. When a skier jumps into the air, the switch opens up by virtue ofthe fact that relatively no weight is on the switch; and this openedswitch is also detected and input into microprocessor subsystem 12. Themicroprocessor subsystem 12 will count at known time intervals (clockrates) for the duration of the opened switch, corresponding to the jump,and will record how long the jump lasts.

As described in connection with FIG. 3, the “air” time may be recordedas a single jump, or recorded as a successive list of jumps. Inaddition, the “air” time can be summed or integrated into a runningtotal, such as described above.

FIG. 6 illustrates the manner in which one switch is formed, in accordwith the invention (for illustrative purposes, the drawing of FIG. 6,like most of the drawings herein, are not to scale; and further showsdisproportionate sizes of elements of the invention at least). A boot100 (e.g., the ski boot 30 of FIG. 2) rests on top of a compressiblematerial 102, e.g., foam, that includes a switch 104. When the usersteps on the compressible material 102, the compressible material 102compresses and causes the switch 104 to close, completing the circuit106 (for illustrative purposes, the circuit 106 is shown simply as aswitch 104, battery 108 and resistor 110; and the circuit 106 is shownexternally when in fact the circuit is within the system of theinvention and in communication with the microprocessor subsystem 12).When the switch 104 is closed, the circuit is in an ON condition, andwhen the switch 104 is not closed, the system is in an OFF condition.Accordingly, the microprocessor subsystem 12 senses the ON and OFFconditions to calculate “air” time. Specifically, the time between anOFF condition and an ON condition can be used to determine “air” time.

Another embodiment of the invention which is suitable for use as theloft sensor 20, FIG. 1, includes a pad that is placed under the skier'sboot and that changes capacitance as a function of a change of appliedpressure. For example, consider FIG. 7 (again with illustrative ski boot100) which shows a compressible material 112 and a capacitance-changingelement 114 that changes capacitance under varying applied pressures.This capacitance-changing element 112 is connected in circuit 116,including the illustrative battery element 118 and resistor 120, withthe system of the invention such that its capacitance is converted to adigital signal by conditioning electronics, such as shown in FIG. 8. Asabove, the circuit of FIG. 7 is shown illustratively and without theother necessary components (e.g., the microprocessor subsystem) of theinvention. Those skilled in the art understand that the components 112,114, 115, 116, 118 and 120 connect integrally with a system (e.g., thesystem 10 of FIG. 1) constructed according to the invention.

By way of background, a capacitor consists of two parallel platesseparated by a dielectric material. The capacitance is directlyproportional to the cross sectional area of the plates and inverselyproportional to the distance between the plates. When the dielectric isthe compressible material 112, FIG. 7, then the pressure applied to thematerial 112 changes the distance between the plates 115 a, 115 b of thecapacitance-changing element 114, thereby proportionately increasing thecapacitance.

FIG. 8 shows a monostable multivibrator 122, e.g., a NE555, in accordwith the invention which converts the varying capacitance (illustratedas portion 124) from the capacitance-changing element 114 of FIG. 7 toinformation suitable for calculating “air” time. A resistor 126 connectsin circuit with the portion 124 and the multivibrator 122. The outputpulse train 128 is directly dependent on the product of the resistance“R” and variable capacitance “C”. The resistance R may be fixed whilethe capacitance C is dependent on the pressure exerted on the pad 112thus shifting the frequency of a pulse train 128. The pulse train 128repetition rate is indicative of the value of capacitance of 124. Whenthe pulse train 128 repetition rate increases the value of C 124 hasdecreased and the skier's boot is applying less pressure on the pad 112.This event marks the beginning of the “air time” measurement. When thepulse train 128 repetition rate decreases, meaning a sudden increase ofcapacitance, the boot is now applying greater pressure on the ski,signifying the end of the “air” time measurement. The length of timethat the pulse train 128 remains at the higher repetition rate is equalto the amount of time the ski is off the ground. That amount of time isthe loft or “air” time.

Alternatively, and such as shown in FIG. 9, the change in capacitancecan be used in a filter which passes a pulse train during lowcapacitance levels (no boot pressure) and which filters out the pulsetrain during high capacitance events (high boot pressure). For example,a capacitance-changing element 130 (e.g., the capacitance-changingcircuit 116 of FIG. 7) connects to the input of a Schmidtt Trigger CMOSgate 133 and ground. A pulse generator 131 connects through a fixedresistor R 132 to the capacitance-changing element 133 and the SchmidttTrigger CMOS gate 133 . The pulse generator 131 produces a steady pulsetrain 134. When the capacitance changing element 130 is at a highcapacitance, corresponding to a high boot pressure meaning that the skiis on the ground, the combination of the fixed resistance R 132 and thecapacitance of the capacitance-changing element 130 absorbs the pulsetrain and the output of the Schmidtt Trigger CMOS gate 133 is constant.On the other hand, when the skier takes flight, the capacitance of thecapacitance-changing element 130 is low, thus allowing the pulse train134 to pass through to the Schmidtt Trigger CMOS gate 133 input. Theoutput of the Schmidtt Trigger CMOS gate 133 in this latter case togglesat the same rate as the pulse train 131, thereby identifying a conditionof “air” time. A discrete input is thus used by the processor to samplefor the existence of the pulse train to calculate “air” time.

Microprocessor Subsystem

The microprocessor subsystem 10 of FIG. 1 can include a microcontrollerelement, a microcontroller element with reduced functionality toconserve power, or a microprocessor element with associated memory andlogic to perform the requisite calculations of the invention, includingthe processing power to drive the display 16 and user interface 14.

Preferably, however, the microprocessor subsystem 12 is constructed byseveral known components, such as shown in FIG. 10. FIG. 10 showsmicroprocessor subsystem 150 constructed according to the invention andincluding a Central Processing Unit (CPU) 152, memory 154, interfaceelectronics 156, and conditioning electronics 158. The user interface160, such as the interface 14 of FIG. 1, and including the button inputsof FIG. 3, connects to the subsystem such as shown and directly to theconditioning electronics 158. The display 162, such as the display 16 ofFIG. 1, preferably connects to the subsystem such as shown and directlyto the CPU 152.

The CPU 152 includes a microprocessor 152 a, Read Only Memory (ROM) 152b (used to store instructions that the processor may fetch in executingits program), Random Access Memory (RAM) 152 c (used by the processor tostore temporary information such as return addresses for subroutines andvariables and constant values defined in a processor program), and amaster clock 152 d. The microprocessor 152 a is controlled by the masterclock 152 d that provides a master timing signal used to sequence themicroprocessor 152 a through its internal states in its execution ofeach processed instruction. The clock 152 d is the master time sourcethrough which time may be deduced in measuring velocity or air time (forexample, to determine the elapsed time from one event to another, suchas the lapsed time “t1” to “t2” of FIG. 4, the clock rate provides adirect measure of time lapse).

The microprocessor subsystem 150, and especially the CPU 152, arepreferably low power devices, such as CMOS; as is the necessary logicused to implement the processor design.

The subsystem 150 stores information about the user's activity inmemory. This memory may be external to the CPU 152, such as shown asmemory 154, but preferably resides in the RAM 152 c. The memory may benonvolatile such as battery backed RAM or Electrically ErasableProgrammable Read Only Memory (EEPROM). External signals 164 from thespeed and/or loft sensors, e.g., the speed sensor 18 and loft sensor 20of FIG. 1, are connected to the conditioning electronics 158 whichfilters, scales, and, in some cases, senses the presence of certainconditions, such as zero crossings. This conditioning essentially cleansthe signal up for processing by the CPU 152 and in some casespreprocesses the information. These signals are then passed to theinterface electronics 156, which converts the analog voltage or currentsto binary ones and zeroes understood by the CPU 152.

The invention also provides for intelligence in the signal processing,such as achieved by the CPU 152 in evaluating historical data. Forexample, “air” time may be determined by the noise spectra that changesabruptly, such as indicating a leap, instead of a noise spectrarepresenting a more gradual change that would occur for example when askier slows to a stop. As previously noted, a minimum quiet time isrequired, in certain embodiments of the invention, to differentiatebetween “air” time and the natural motions associated with turning andskiing (e.g., jump skiing). Further, in other certain embodiments, amaximum time is also programmed to differentiate “air” time from anabrupt stop, such as standing in a lift line.

Speed Sensor

In accord with the invention, if speed is calculated within the system,the speed sensor 118 of FIG. 1 can take one of several forms, including:(1) a pitch detection system that detects the “pitch” of the vibrationalspectrum and that converts the pitch to an equivalent speed; (2) alaser-based or sound-based Doppler-shift sensor; (3) anaccelerometer-based speed sensor; (4) a pressure-based speed sensor; and(5) a voltage-resistance sensor

It should be noted that in either of the speed or loft sensors, it maybe preferable to incorporate state machine logic within the sensor inorder to pre-process the data for the microprocessor subsystem. Thus, inaccord with the invention, processing logic such as described herein inconnection with the microprocessor subsystem can be incorporated, atleast in part, within one or both of the speed and loft sensors. Becauseof the complexity of the speed sensor, such preprocessing power is moreappropriately within the speed sensor.

Speed Sensor: Pitch Detection

In accord with this embodiment, no separate speed sensor element, e.g.,the sensor 18 of FIG. 1, is required. Rather, the vibrational spectrumthat is generated by the loft sensor 20, and particularly theaccelerometer or microphone embodiment discussed in connection with FIG.4, will be used to determine the pitch of the vibration and, thereby,the equivalent speed. By way of example, note that a skier generates ascraping sound on hard-packed snow and ice. When the skier changesvelocity, that scraping sound changes in pitch. The spectrum shown inFIG. 4 outside the t1/t2 region (but within the “start” and “end”region) is, effectively, that pitch. By calibrating the microprocessorsubsystem 12 to associate one pitch as one velocity, and so on, thespeed of the vehicle (e.g., ski and mountain bike) may be determined byspectral content.

In accord with the invention, one method for determining the “pitch” ofthe spectrum outside the t1/t2 loft region of FIG. 4 (and within thestart/stop time) is to determine the “best fit” sine wave to thevibrational spectrum data. This sine wave will have a frequency, or“pitch” that may be quantified and used to correlate velocity.

This spectral content may be determined, in part, by the conditioningelectronics 158 of FIG. 10 such to determining rise times to infer abandwidth of the information. The conditioning electronics 158 and/orCPU 152 can also measure the time between successive zero crossings,which also determines spectral content.

For example, FIG. 11 illustrates a spectrum 166 generated from a sensorsuch as a sensor 18 or 20 (FIG. 1), or 82 (FIG. 5), or 202 a-202 d (FIG.13 below). The spectrum 166 thus represents an acceleration spectrum orsound spectrum such as described herein. The microprocessor subsystem 12of FIG. 1 evaluates the spectrum 166 and generates a best-fit sine wave167 to match the primary frequency of the spectrum 166 over time. FIG.11 shows illustratively a situation where a vehicle, such as a ski,moves slowly at first, corresponding to a lower sine-wave frequency,then faster, corresponding to a higher frequency sine wave, and thenslower again. This pitch transition is interpreted by the microprocessorsubsystem (e.g., the subsystem 12 of FIG. 1) as a change of speed.Specifically, the microprocessor subsystem of the invention iscalibrated in this embodiment to associate a certain frequency with acertain speed; and speed is thus known for the variety of pitchesobserved during an activity, such as illustrated in FIG. 11.

It should be noted that the pitch information is surface dependent (andvehicle dependent). That is, a ski-over-snow-speed-spectrum has adifferent spectrum than a bicycle-over-ground-spectrum. Accordingly,different calibrations must be made for different vehicles and speeds,in accord with the invention. Further, certain spectrums may actuallydecrease in frequency as speed increases; which also must be calibratedto obtain the correct speed information. These calibrations aretypically programmed into the microprocessor subsystem memory, e.g., thememory 13 of subsystem 12 of FIG. 1. Further, in certain embodiments ofthe invention, the system stores different spectrum calibrations fordifferent activities so that a user can move the system from one sportto another. Accordingly, one or more buttons such as the buttons 58-67of FIG. 3 are introduced to the user interface, such as known to thoseskilled in the art, in order to selectively access the differentspectrum calibrations.

Speed Sensor: Doppler-based

It is well known that Doppler radar is used by police vehicles to detectspeed. In accord with this embodiment of the invention, the sameprinciples apply to the measurement of speed of the sporting vehicle.For example, consider FIG. 12.

FIG. 12 shows a representative ski 170 (partially shown) with aDoppler-based sensor 172 mounted thereon (for illustrative purposes, theDoppler-based sensor is shown without the other elements of the system,such as the user interface and microprocessor). The sensor generates anelectromagnetic beam 174, such as a laser beam, to bounce off the ground176 (e.g., the ski slope) while the user of the system conducts theactivity (e.g., skiing). The electromagnetic beam 174 is reflected offthe ground by particles 178 which scatter at least a portion of theenergy back to the sensor 172 along approximately the same path. Becausethe ski 170 is in motion, the returned energy is at a slightly differentfrequency from the outgoing frequency; hence the Doppler shift, which isa measurable quantity. Note that the sensor 172 must be arranged togenerate a beam along the side (or in front or back of) the ski in orderto “see” the ground 176.

The energy beam 174 is generated in one of two general ways: by a laserdiode (to generate a laser beam) or by a piezoelectric transducer (toproduce an ultrasonic beam). FIG. 12a, for example, shows a sensor 172′comprising a laser diode 180. The diode 180 generates a laser beam 174′which is reflected by the particles 178′ back to the sensor 172′. Asmall beam-splitting mirror 182 reflects part of the returned beam to adetector 184 which is connected under the overall control of themicroprocessor subsystem 186, e.g., the subsystem 12 of FIG. 1 (forillustrative purposes, the other elements of the system of theinvention, e.g., the user interface, are not shown in FIG. 12a). Thesubsystem 186 evaluates the frequency difference between the outgoingbeam from the diode 180 and the returned frequency from the detector184. The frequency difference is readily converted to speed that isdisplayed on the display, e.g., the display 16 of FIG. 1.

Likewise, FIG. 12b shows a sensor 172″ comprising a piezoelectrictransducer 190 which generates an ultrasonic beam 174″ that reflectsfrom particles 178″ back to the piezo transducer 190, which is connectedunder the overall control of the microprocessor subsystem 192, e.g., thesubsystem 12 of FIG. 1 (for illustrative purposes, the other elements ofthe system of the invention, e.g., the user interface, are not shown inFIG. 11b). The microprocessor subsystem 192 generates a voltage at a setfrequency to drive the piezoelectric transducer 190, to thereby generatethe beam 174″. The reflected Doppler-shifted beam returns through thetransducer 190 (alternatively, through another piezo transducer (notshown)) and generates a voltage at the frequency of the reflected beam.The subsystem 192 evaluates the frequency difference between theoutgoing ultrasonic beam 174″ and the returned frequency. As above, thefrequency difference is readily converted to speed (via a conversiontechnique that is known to those skilled in the art) that is displayedon the display, e.g., the display 16 of FIG. 1.

Loft Sensor: Accelerometer Based

Modern navigation systems utilize a plurality of accelerometers todetermine speed and direction. Particularly complex military systems,for example, utilize three translational and three rotationalaccelerometers to track direction and speed even during complex angularmovements and at extremely high velocities.

In accord with the invention, a similar plurality of accelerometers isused to determine speed. However, unlike military systems, one goal ofthe invention is to track speeds of sporting vehicles (e.g., a ski) thatgenerally travel in one direction, namely forward. Therefore, thecomplexity of the accelerometer package is reduced since the orientationof the sensor may be fixed to the vehicle; and fewer than sixaccelerometers can be used to determine speed.

Accelerometers are well-known to those skilled in the art. They include,for example, translational and rotational accelerometers. FIG. 13illustrates a speed sensor 200 constructed according to the inventionand which includes a plurality of accelerometers 202 a-202 d. Theaccelerometers 202 a-202 d sense various accelerations in theirrespective axes (accelerometers sense acceleration along a predefinedaxis, translational or rotational), and each of the outputs from theaccelerometers are input to the microprocessor subsystem 204, e.g., thesubsystem 12 of FIG. 1, via communication lines 206 a-206 d. Theorientation of the sensitive axis of each accelerometer 202 a-202 d isstored in the microprocessor subsystem 204 so that a particularacceleration in one axis is properly combined with acceleration valuesin other axes (as described in more detail below in connection withFIGS. 14 and 14a).

One key point that must be addressed with the accelerometer-basedapproach: gravity has a huge effect on the accelerometer signals; andgravity must be compensated for in order to achieve reasonable speedaccuracy. Therefore, one or more of the accelerometers 202 a-202 d areused to determine and measure the force or gravity relative to the angleof the vehicle (e.g., the ski) so that gravity may be compensated for bythe subsystem 204. Specifically, when the sensor 200 is pointed eitherdownhill or uphill, gravity tends to reduce or increase the measuredacceleration output; and that reduction or increase must be adjusted foror else the conversion from acceleration to speed (i.e., the integral ofacceleration over time) will be next to useless. Accordingly, theorientations of the accelerometers 202 a-202 d relative to theirrespective sensitive axes must be known by the subsystem 204 in order tocompensate for the acceleration of gravity, which is generallyperpendicular to the motion of the vehicle, but which has a componentacceleration in the direction of movement when the vehicle is pointeddownwards or upwards.

It should be clear to those skilled in the art that fewer, or greater,numbers of accelerometers are within the scope of the invention, so longas they collectively determine speed. In effect, the fewer number ofaccelerometers results in reduced accuracy; not reduced functionality.Rather, in an ideal situation, one accelerometer can be used to detectspeed; which is the integral of the acceleration over time. Further, adouble integration over the same period provides distance; and,therefore, the invention can also provide distance in at least oneembodiment of the invention.

It should also be noted that any of the accelerometers 202 a-202 d ofFIG. 13 can be used, in accord with the invention, as the loft sensor 20of FIG. 1 and without a separate component to measure “air” time. Thisis because each of the accelerometers 202 a-202 d generate a spectrumsuch as described in connection with FIG. 4. Accordingly, one or more ofthe accelerometers 202 a-202 d can be used to determine “air” time,described above, without the need for a separate loft sensor.

FIG. 14 schematically illustrates process methodology, according to theinvention, which converts a plurality of acceleration inputs to speed.For example, when a plurality of six accelerometers (e.g., similar tothe accelerometers 202 a-202 d of FIG. 13) are connected to amicroprocessor subsystem such as the subsystem 150 of FIG. 10, theprocess methodology of the invention is preferably shown in FIG. 14.Specifically, six accelerometers are connected with various sensitiveorientations to collect pitch 207 a, yaw 207 b, roll 207 c, surge 207 d,heave 207 e, and sway 207 f accelerations. These accelerations areconditioned by the conditioning electronics 158′ through the interfaceelectronics 156′ and CPU 152′ to calculate speed, such as known to thoseskilled in the art of navigational engineering (for example, GyroscopicTheory. Design, and Instrumentation by Wrigley et al., MIT Press (1969);Handbook of Measurement and Control by Herceg et al, SchaevitzEngineering, Pensauker, N.J., Library of Congress 76-24971 (1976); andInertial Navigation Systems by Broxmeyer, McGraw-Hill (1964) describesuch calculations and are hereby incorporated herein by reference). Theelements 158′, 156′ and 152′ are similar in construction to the elements158, 156 and 152 described in connection with FIG. 10.

FIG. 14A schematically illustrates further process methodologiesaccording to the invention wherein the six acceleration inputs 207 a-207f are processed by the microprocessor subsystem of the invention (e.g.,subsystem 12 of FIG. 1) such that centripetal, gravitational, and earthrate compensations are performed so that the various accelerations areproperly integrated and compensated to derive speed (and even directionand distance). Specifically, a microprocessor subsystem of the FIG. 14Aembodiment includes a centripetal acceleration compensation section 208a which compensates for motions of centripetal accelerations via inputsof surge 207 d, heave 207 e, and sway 207 f. A gravity accelerationcompensation section 208 b in the subsystem further processes theseinputs 207 d-207 f to compensate for the acceleration of gravity, whilea earth rate compensation section 208 c thereafter compensates for theaccelerations induced by the earth's rotation (e.g., the earth rateacceleration at the equator is approximately opposite in direction tothe force of gravity).

Also shown in FIG. 14A are translational integrators 209 a-209 c whichconvert the compensated accelerations from inputs 207 d-207 f totranslational velocities by integration. Integrators 210 a-210 clikewise integrate inputs of pitch 207 a, yaw 207 b, and roll 207 c toangular velocity while integrators 211 a-211 c provide a furtherintegration to convert the angular velocities to angular position. Theangular positional information and translational velocity information iscombined and processed at the speed and direction resolution section 212to derive speed and direction. Preferably, the subsystem with thecomponents 208, 209, 210, 211 and 212 is calibrated prior to use; andsuch calibration includes a calibration to true North (for a calibrationof earth rate).

It should be noted that fewer of the inputs 207 a-207 f may be used inaccord with the invention. For example, certain of the inputs 207 a-207f can be removed with the section 208 a so that centripetal accelerationis not compensated for. This results in an error in the calculated speedand direction; but this error is probably small so the reducedfunctionality is worth the space saved by the removed elements. However,with the increased functionality of the several inputs 207 a-207 f, itis possible to calculate loft height in addition to speed becausedistance in three axes is known. Therefore, the invention furtherprovides, in one embodiment, information for displaying height achievedduring any given “air” time, as described above.

It should be apparent to those in the art that the accelerometers ofFIGS. 13-14 provide sufficiently detailed information such that thewhole of the system according to the invention can be mounted to a userof the system directly, rather than directly to a vehicle. With thescope of the compensations described in connection with FIG. 14A, forexample, movements of the human body, e.g., centripetal motions, may becompensated for to derive speed and/or loft time information that isuncorrupted by the user's movements. Such compensations, however,require powerful processing power.

Speed Sensor: Pressure Based

Pressure of the air is used in aviation to determine how high anaircraft is. The higher the altitude the lower the air pressure.Pressure sensors according to the invention convert air pressure to ananalog voltage. When mounted to a snowboard 220, such as shown in FIGS.15 and 15A, the pressure sensor 221 is used to determine the altitude ofthe snowboarder. This voltage is read by the microprocessor subsystem(e.g., the subsystem 12 of FIG. 1) at a fixed rate and differentiated todetermine rate of descent or speed in the vertical direction. This maybe converted to speed along the path by knowing the grade or angle ofdescent. Angle of descent is known by predetermiring the geometry of theski path or by the addition of a inclinometer 222 which gives a voltagedependent upon the angle, with respect to vertical, of the platform. Theinclinometer 222 measures zero when the ski is traveling along a levelpath and the pressure sensor is showing a constant pressure. When theski moves downhill, for example, the inclinometer 222 measures the angleof descent and the pressure sensor measures ever increasing pressure.Since the angle of descent is known, as is the rate of descent, the truespeed is determined and displayed.

Those skilled in the art should understand that the elements 221 and 222are connected in circuit with the further elements of the invention,e.g., the microprocessor subsystem 12 of FIG. 1; and that elements 221and 222 are shown in FIG. 15 for illustrative purposes only when in factthey exist integrally with the system of the invention, e.g., the system10 of FIG. 1.

Speed Sensor: Voltage-Resistance Based

Under-water vehicles and many oceanographic instruments measure watervelocity by taking advantage of the principle discovered by Faraday thata conductor moving through a magnetic field produces a voltage acrossthe conductor. The voltage produced is greatest when the conductor isorthogonal to the magnetic field and orthogonal to the direction ofmotion. This principal is used, in accord with the invention, todetermine the speed that a skier moves over the snow in winter skiing orover the water in water skiing. As shown in FIGS. 16 and 16A, anelectromagnet 241 is mounted to a snowboard 242. Two contacts 240 a, 240b are mounted to the snowboard 242 such that the bottom 243 a makescontact with the snow and the top 243 b of the contacts are connected toa voltage-measuring circuit within the conditioning electronics (such asthe electronics 158 of FIG. 10 and such as known to those skilled in theart). When the snowboard 242 is flat on the snow, a conduction path isset up between the two contacts 240 a, 240 b and through the snow. Whenthe electromagnet 241 is energized, a magnetic field 244 is imposed onthe conduction path. As the snowboard 242 moves in the forward direction245, the conduction path through the snow moves with the snowboard 242.This represents a moving conductor in a magnetic field; and as Faraday'stheorem requires, a voltage 246 across the two terminals 240 a, 240 bwill be generated that is proportional to the snowboarder's speed. Thisvoltage 246 is read by the microprocessor subsystem (e.g., the subsystem12 of FIG. 1). When the voltage abruptly goes to zero, and thereafterreturns to a high voltage, the microprocessor subsystem determines thatthe gap in voltage is “air” time. Accordingly, in such an embodiment, noseparate sensor 20 is required to measure “air” time (such as describedabove).

Those skilled in the art will appreciate that the elements of FIGS.16-16B are shown illustratively for ease of understanding and withoutthe further necessary elements of the invention, e.g., themicroprocessor subsystem 12 of FIG. 1.

It should be clear to those skilled in the art that certainmodifications can be made to the invention as described withoutdeparting from the scope of the invention. For example, vehicles otherthan skis and mountain bikes may be used with the invention. Onevehicle, the snowboard, used in the ever popular snowboarding sport, isparticularly well-suited for the invention (e.g., there is no jumpskiing). The snowboard also has a wide body and a system constructedaccording to the invention can be incorporated within the body with theuser interface, display, and associated buttons at the snowboardsurface, for easy access. FIG. 17 shows such an improvement to asnowboard in accord with the invention. Specifically, a snowboard 270,with boot holder 271, incorporates a system 272 constructed according tothe invention. The system 272, like the system 10 of FIG. 1, has adisplay 274, a user interface 276 that provides a user with buttons toselectively access speed and loft time, as described above, and one ormore display portions 278 to display identification information aboutthe displayed times (such as described in connection with FIG. 3).

FIG. 18 shows yet another use of the invention. Specifically, a furtherapplication of the invention is found in the sport of ski jumping andski flying. Ski flying is similar to ski jumping except that ski jumpinguses special, extralong skis, while ski flying uses standard alpineskis. The participant 300 skis down the long ramp 302, which may be ashigh as twenty-five stories, and launches horizontally into the air atthe end 304 of the ramp 302. The objective of the sport is for theparticipant 300 to “jump” or “fly” through the air for as long aspossible, and covering the greatest distance as possible. A systemconstructed according to the invention (not shown) is attached to theski 310 to measure “air” time, speed, and distance, as described herein.In particular, the speed at the end 304 is used to predict distance bywell-known Newtonian physics so that the participant's overall jumpdistance is calculated. This removes the necessity of having judgesand/or other expensive equipment monitor the event, as the recorded“air” and jump distance is readily displayed by the system of theinvention.

It is accordingly intended that all matter contained in the abovedescription or shown in the accompanying drawings be interpreted asillustrative rather than in a limiting sense.

It is also intended that the following claims cover all of the genericand specific features of the invention as described herein, and allstatements of the scope of the invention which, as a matter of language,might be said to fall there between.

What is claimed is:
 1. An apparatus for determining loft time of amoving vehicle off of a surface, the moving vehicle of the type which isridden along the surface by a user of the vehicle, comprising: a loftsensor for sensing a first condition that is indicative of the movingvehicle leaving the surface, and a second condition indicative of themoving vehicle returning to the surface, the loft sensor beingconstructed and arranged so as to be substantially non-interfering withmotion of the moving vehicle along the surface, wherein the loft sensoris selected from the group of (i) an accelerometer that senses avibrational spectrum; (ii) a microphone assembly that senses a noisespectrum; (iii) a switch that is responsive to a weight of a user of themoving vehicle; (iv) a voltage-resistance sensor that generates avoltage indicative of a speed of the moving vehicle; and (v) a pluralityof accelerometers connected for evaluating a speed of the moving vehicleand; a microprocessor subsystem for determining a loft time that isbased on the first and second conditions, wherein the microprocessorsubsystem comprises means for interpreting data from the loft sensor todetermine the loft time from a time difference between the first andsecond conditions.
 2. The apparatus according to claim 1, wherein theloft sensor senses a spectrum of information and wherein the first andsecond conditions correspond to a change in the spectrum of information,and wherein the microprocessor subsystem comprises means forinterpreting the change in the spectrum to determine the loft time. 3.The apparatus according to claim 1, wherein the loft sensor comprises acircuit that is responsive to a weight of the user of the movingvehicle, the circuit having a compressible material and a switch thatcompletes the circuit once the compressible material is compressed, themicroprocessor subsystem having means for detecting whether the circuitis open or closed and for determining the loft time based upon a periodof time when the circuit is closed.
 4. A method for determiningnon-motorized vehicle speed along a surface, the non-motorized vehicleof the type which is ridden along the surface by a user, comprising thesteps of: monitoring a pitch of the non-motorized vehicle caused by themotion of the non-motorized vehicle relative to the surface; correlatingthe pitch to a speed; informing the user of the speed; and comparing thepitch to a calibrated pitch spectrum.
 5. A method for determiningnon-motorized vehicle speed along a surface, the non-motorized vehicleof the type which is ridden along the surface by a user, comprising thesteps of: monitoring a pitch of the non-motorized vehicle caused by themotion of the non-motorized vehicle relative to the surface; correlatingthe pitch to a speed; informing the user of the speed; and correlatingthe pitch with a particular non-motorized vehicle type.